White House chief of staff Denis McDonough is leading outreach to GOP senators on fiscal issues. / Chris Usher, AP

by David Jackson, USA TODAY

by David Jackson, USA TODAY

A top aide to President Obama said Sunday that U.S. policy in Syria has to be dictated in part by what happened in Iraq.

White House chief of staff Denis McDonough, speaking on CBS' Face The Nation, referred to Iraq in saying of Syria: "We've rushed to war in this region in the past; we're not going to do it here."

McDonough added: "We have to be very discerning about what's in our interest and what outcome is best for us, and the prices that we're willing to pay to get to that place."

Obama administration officials -- though not the president himself -- announced last week that they are sending military aid to Syrian rebels, but did not specify that aid.

The administration has provided "robust" assistance to the rebels in recent weeks, McDonough said, and "that assistance will expand. The scope and scale of that assistance will expand."

Critics of the administration's Syria response said the plan amounts to little more than small arms, and is not enough to deter the government forces of Syrian President Bashar Assad. Sen. John McCain, R-Ariz., who opposed Obama in the 2008 election, said the U.S. help is "too little, too late."

Hanging over the discussion of Syria: The problems stemming from the 2003 U.S.-led invasion of Iraq.

In discussing Syria at the White House last week, deputy national security adviser Ben Rhodes said that "we need to be humble here about our ability to solve a problem like Syria, certainly on our own."

Rhodes added: "Recent history teaches us that even when you have U.S. boots on the ground, you're not necessarily going to be able to prevent violence amongst civilian populations. We saw that in Iraq, for instance."